In an ink-jetting recording apparatus such as an ink-jetting printer or an ink-jetting plotter, a recording head is caused to move in a main scanning direction, and a recording paper (a kind of recording medium) is caused to move in a sub-scanning direction. In cooperation with those movements, a drop of ink can be ejected from a nozzle of the recording head onto the recording paper. Thus, an image (including a character or the like) can be recorded on the recording paper. For example, the drop of ink can be ejected by causing a pressure chamber communicating with the nozzle to expand and/or contract.
The pressure chamber may be caused to expand and/or contract, for example by utilizing deformation of a piezoelectric vibrating member. In such a recording head, the piezoelectric vibrating member can be deformed based on a supplied driving-pulse in order to change a volume of the pressure chamber. When the volume of the pressure chamber is changed, a pressure of the ink in the pressure chamber may be changed. Then, the drop of ink is ejected from the nozzle.
In such a recording apparatus, a driving signal consisting of a series of a plurality of pulses-waves is generated. On the other hand, printing data including level (gradation) information can be transmitted to the recording head. Then, based on the transmitted printing data, only necessary one or more pulse-waves are selected from the driving signal and supplied to the piezoelectric vibrating member. Thus, a volume of the ink ejected from the nozzle may be changed based on the level information.
On the other hand, in a recording head for color printing, a plurality of rows of nozzles is alongside arranged for respectively ejecting a plurality of color inks. When the respective color inks are suitably ejected to be overlapped, the color recording is desirably achieved. The plurality of color inks are, for example, a black ink, a cyan ink, a magenta ink, and a yellow ink.
For example, in an example shown in FIG. 13, in a recording head for color printing, a row of nozzles for ejecting a black ink (BK), a row of nozzles for ejecting a cyan ink (C), a row of nozzles for ejecting a magenta ink (M) and a row of nozzles for ejecting a yellow ink (Y) are arranged alongside in this order.
The nozzle pitch of each row of nozzles of FIG. 13 is 120 dpi. In order to achieve a recording density of 360 dpi in the recording head, it is sufficient to divide one nozzle pitch into three and to carry out a three-path main scanning operation. Thus, if a resolution in a main scanning direction is also set at 360 dpi, a resolution of 360×360 dpi can be obtained (normal mode).
On the other hand, for the purpose of printing a draft document or the like, a higher-speed recording operation may be desired. In this case, high printing quality is not required. In such a case, only a black ink is used, and a one-path main scanning operation is carried out for one nozzle pitch. That is, since a resolution in a sub scanning direction is maintained at 120 dpi, a dot resolution is 360×120 dpi (high-speed black mode).
In general, a plurality of nozzles is formed in a matrix pattern as shown in FIG. 13. However, each row of nozzles may be shifted for various purposes (JP Laid-Open Publication No. Hei4-290751; JP Laid-Open Publication No. Hei6-171084; JP Laid-Open Publication No. Hei8-39798; and JP Laid-Open Publication No. 2002-113852).